1. Field of the Invention
This invention relates to brushless direct current motors and specifically to a phase current reconstruction circuit for reconstructing a plurality of phase current waveforms for a brushless direct current motor having a plurality of phase windings.
2. Description of the Prior Art
Phase current reconstruction circuits for reconstructing the phase current waveforms for a brushless direct current motor have been designed for low voltage brushless direct current motors. However, a phase current reconstruction circuit which operates equally well at all motor voltage ranges is heretobefore unknown.
Additionally, previous high voltage motor circuit implementations have employed rather complex current sensor elements, such as the LEM. LEM is a commercially available current transducer for the measurement of AC and DC currents providing galvanic isolation between the primary (high power) and secondary (signal) circuits. The present invention uses nothing more than a simple differential amplifier and an associated sense resistor for its current sensor. This simple and low cost circuit lends itself to implementation as a single integrated circuit component.